Methods are known for producing diagnostic test elements by coating a carrier foil with a bilayer test material structure, which is sequentially coated with a doctor knife as an aqueous suspension. In this context, it is also known to monitor a layer in the wet state by means of an infrared (IR) spectrometer. Only afterwards, the drying of the coating is carried out. IR spectrometry, however, only registers a water content of the coating and not a proportion of functional ingredients. Moreover, only a relative signal is achieved in this way to evaluate the homogeneity of the measured layer within a production batch. A measurement on the final dry product (e.g., a test element) is not possible in such a way.
In the field of semiconductor wafer fabrication, U.S. Pat. No. 5,657,363 discloses using radioisotopic X-ray fluorescence to investigate thin metal films on a semiconductor substrate.
On this basis, an object of this disclosure is to further improve known methods and systems for producing layered, diagnostic test elements including areal coating determination and to provide improved quality control not only when producing test elements but also when using such test elements in an analyte measurement process.